package QizhongKaoshi;
import java.util.Scanner;
public class Kaoshi4 {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        Circle c1=new Circle();
        Circle c2=new Circle();
        Circle c3=new Circle();
        int a,b;
        a=scanner.nextInt();
        b=scanner.nextInt();
        c1.Circle();
        System.out.println(c1.toString());
        System.out.println(String.format("%.2f",c1.getArea()));
        c2.Circle();
        System.out.println(c2.toString());
        System.out.println(String.format("%.2f",c2.getArea()));
        c2.set(a);
        System.out.println(c2.toString());
        System.out.println(String.format("%.2f",c2.getArea()));
        c3.Circle(b);
        System.out.println(c3.toString());
        System.out.println(String.format("%.2f",c3.getArea()));
    }
}
class Circle{
    private int radius;
    void Circle(){
        radius=2;
        System.out.println("This is constructor with no para");
    }
    void Circle(int radius){
        if(radius>0){
            this.radius=radius;
            System.out.println("This is constructor with para");
        }
    }
    void set(int radius){
        if(radius>0){
            this.radius=radius;
        }
    }
    double getArea(){
        double s=Math.PI*radius*radius;
        return s;
    }
    public String toString(){
        return "Circle[radius="+radius+"]";
    }
}